![]() ![]() Royal Observatory, Greenwich, Great Britain Įquatorial Group, Herstmonceux, Sussex Alvan Clark & Sons mounting replaced with Warner & Swasey mounting in 1893. Moved to Northwest, Washington, D.C., 1893 Destroyed by bush fire on January 18, 2003. ![]() Yale-Columbia Refractor - Previously located in South Africa. Yale-Columbia Refractor moved to Mount Stromlo Observatory in 1952, same telescope as following entry. Still in operation for educational purposes. Single element non-achromatic objective with Schupmann corrector. The lens is 110 cm in diameter stopped down to 98 cm.ĭouble telescope by Repsold and Sons, optics by SteinheilĪllegheny Observatory, University of Pittsburghĭestroyed during WWII, only lens (made by Alvan Clark & Sons) survives. Single element non-achromatic objective combined with reflective Adaptive optics and a Schupmann corrector. Great Paris Exhibition Telescope of 1900 įixed lens, scrapped. It is a single element lens whereas most of this list are doublets, with a crown and flint lens elements. The SST has an optical aperture of 98 cm (39.37"), although the lens itself is 110 cm (43.31"). This list includes some additional examples, such as the Great Paris telescope, which also used a mirror, and some solar telescopes which may have more complicated optical configurations. As with reflecting telescopes, there was an ongoing struggle to balance cost with size, quality, and usefulness. Larger meniscus lenses have been used in later catadioptric telescopes which mix refractors and reflectors in the image-forming part of the telescope. Using a siderostat incurs a reflective loss. It used a 78-inch (200 cm) Focault siderostat for aiming light into the Image-forming optical system part of the telescope, which had a 125 cm diameter lens. However, other large refractors include a 21st-century solar telescope which is not directly comparable because it uses a single element non-achromatic lens, and the short-lived Great Paris Exhibition Telescope of 1900. Most are classical great refractors, which used achromatic doublets on an equatorial mount. The next largest refractor telescopes are the James Lick telescope, and the Meudon Great Refractor. The Swedish 1-m Solar Telescope, which has an actual lens diameter of 43 inches, is technically then larger than the lens of the Yerkes, but only 39 inches are clear for the aperture, and is used today for solar observations. The largest refracting telescope in the world is the Yerkes Observatory 40 inch (102 cm) refractor, used for astronomical and scientific observation for over a century. Refracting telescopes use a lens to focus light. The additional lens is there to produce an erect image.The Grande Coupole for the double refractor of Meudon, with roughly 83 cm (33 in) and 62 cm (24 in) aperture lenses on the same mounting, and making its debut in 1891. (iii) The astronomical telescope consists of two convex lenses whereas the terrestrial telescope consists of three lenses. (ii) The final image in the astronomical telescope is inverted whereas that in the terrestrial telescope is erect. (i) Astronomical telescopes are used for viewing distant stars and planets whereas terrestrial telescopes are used for viewing distant objects on earth. The magnifying power of a telescope depends on the focal length of both lenses.ĭifferences between astronomical and terrestrial telescopes: The smaller the area, the brighter the image. Brightness of images also depends on how big an area the image light is spread over. The larger the lens, the more light the telescope can gather. The light-gathering power of a telescope is directly proportional to the area of the objective lens. The brightness of an image from a telescope depends partly on how much light is collected by the telescope. The longer the focal length, the larger the image. The size of an image produced by a lens is proportional to the focal length of the lens. Here the image of the distant object formed by the objective acts as the object for the eyepiece. The larger lens is called the objective lens, and the smaller lens used for viewing is called the eyepiece lens. This type of telescope is called a refracting telescope.Ī (refracting) telescope consists of two convex lenses. They focus the light and make distant objects appear brighter, clearer and magnified. Terrestrial and Astronomical Telescope Telescopes use lenses to gather more light than the human eye could collect on its own. ![]()
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